This invention relates to the protection of combustible materials.
One approach to fire protection of combustible materials in vessels, such as plastic containers packaged in corrugated boxes, has been to use fire-retardant corrugated paperboard packaging materials, which may be fire-retarded by an applied spray or impregnation method. Another approach has attempted to protect large plastic intermediate bulk containers, often holding hundreds of gallons of combustible liquid, by placing the primary liquid container beneath an insulating blanket or inside of a metallic outer enclosure (sometimes referred to in the industry as a “spam can”.
Both of these “traditional” approaches attempt to delay or prevent failure of a packaging system by reducing heat transfer to and/or slowing combustion of outer or intermediate layers of packaging material. Both of these approaches rely on concentric protection layers, with the outermost layer being non-combustible or fire-retardant. However, these approaches are often deficient in buildings protected by automatic fire sprinkler systems, because they can delay the operation of the sprinklers, which otherwise control or suppress the fire.
Packaging systems using non-combustible or fire-retardant outer shell materials can be counter-productive in a building equipped with a fire sprinkler system because of reduction of initial fire growth and flamespread across surfaces of stored goods, required for rapid operation of the sprinklers that are necessary for fire control. By delaying operation of fire sprinklers, the period of un-mitigated fire exposure to stored goods is extended. Extended exposure to a severe fire will cause failure of traditional package protection systems (described above) by eventually consuming a fire-retarded combustible exterior layer or, in the case of a “spam can”, transferring sufficient heat to a liquid container inside to cause the container to fail and release its contents. Such a release of contents has been repeatedly demonstrated to be catastrophic, resulting in fires that exceed the capability of traditional fire sprinkler systems.
An additional disadvantage of the “spam can” design is that the metallic exterior is not absorbent, which limits the effectiveness of sprinklers in pre-wetting containers that have not yet been damaged by fire. Absorbent exterior surfaces, such as those made of corrugated paperboard, have the advantage of absorbing water from sprinkler discharge, which pre-wets packages surrounding a fire and delays their ignition.